Kosterlitz-Thouless Transition of the XY model on rewired square lattices
Tasrief Surungan
Abstract
The ferromagnetic XY model (O(2) symmetry) on decorated square lattices is \nstudied via Monte Carlo simulation to probe the role played by an increase in coordination \nnumber on the existing Kosterlitz-Thouless (KT) transition [1]. It is a unique transition between \nthe quasi-long range order (QLRO), also called the KT phase, and the paramagnetic phase at \nhigher temperature [2, 3]. The QLRO is the only type of order allowed by theMermin-Hohenberg \ntheorem for two dimensional (2D) spin model with continuous symmetry [4]. In diluted square \nlattices, where some links are depleted, it was found that the KT phase remains so long as the \nlinks are percolated. Here we probe whether the increase in average number of links preserves \nor destroys the KT phase. The decorated lattice is obtained by adding an extra link to each site \nof a square lattice, randomly connecting each site to one of its next-nearest neighbors [5]. The \naverage number of nearest links increases from two to three, which corresponds to an increase \nin dimensionality. The existence of KT phase is characterized by the correlation ratio, which \nwas also used in characterizing the critical properties of the 2D edge-cubic model [6]. It was \nfound that the KT phase shifted to higher temperature, which indicates that the KT phase on \ndecorated lattices is more robust against thermal fluctuation compared to that of the native \nsquare lattice. [3]. \nReferences